A data center is a facility used to house computing systems and associated components, such as telecommunications and storage systems. A data center can occupy one room of a building, one or more floors, or an entire building. The equipment is typically in the form of servers mounted in cabinets, which are usually placed in single rows forming corridors (so-called aisles) between them. This allows people access to the front and rear of each cabinet. The data center typically additionally includes redundant or backup power supplies, redundant data communications connections, environmental controls (e.g., air conditioning, fire suppression), and security devices.
Manufacturers of data center equipment continue to increase compute capability of servers while at the same time improving compute efficiency and decreasing the server size. However, the power consumption of such servers is also rising despite efforts in low power design of integrated circuits. With the increased power consumption comes a commensurate increase in concentrated heat loads produced by the servers, network equipment, and storage facilities. The heat dissipated by this equipment is exhausted into the data center room. The heat collectively generated by densely populated racks can have an adverse effect on the performance and reliability of the equipment in the racks, since the equipment relies on the surrounding air for cooling. In addition to temperature, humidity can have an adverse effect on data center equipment. If the humidity is too high, water may begin to condense on internal components. If the humidity is too low, static electricity discharge may damage components. Accordingly, precisely controlling the environment in a data center is critical to maximizing availability and performance of essential equipment. And the challenges of cooling these spaces mount as the move to smaller servers results in significantly higher power consumption and more heat generation.
Heating, ventilation, and air conditioning (HVAC) systems required to control the temperature and humidity of the data center have been estimated to account for between twenty five to forty percent of power usage in data centers. Accordingly, HVAC systems are often an important part of the design of an efficient data center. In particular, infrastructure manufacturers and data center designers and operators are focusing on reducing power consumption from the non-compute part of the overall power load, which includes the HVAC systems, in order to achieve significant cost savings.